Anne Bjørg Tveit

Longevity of posterior dental restorations and reasons for failure

Tooth-coloured restorative materials are being used increasingly more often in Class II preparations in permanent teeth. Using a practice-based study design, we aimed to assess the survival time of Class II restorations and to identify factors relevant to their longevity. Class II restorations (n = 4,030), consisting of resin composites (81.5%), compomers (12.7%), amalgams (4.6%), and glass-ionomer cement restorations (1.2%), were placed in 1,873 patients with a median age of 15 yr. In total, 92.7% of restorations were placed due to primary caries and 5.8% were replacements. After an average follow-up period of 4.6 yr, 61.6% of the restorations were successful, 11.2% had failed, and 27.2% were not available for evaluation (owing to patient drop-out). The mean annual failure rate was 2.9% for resin-composite restorations and 1.6% for amalgams. For resin-composite restorations, secondary caries was the most common reason for replacement (73.9%), followed by loss (8.0%), fracture (5.3%), and marginal defects (2.4%). Multilevel Cox-regression analyses identified young age of the patient, high previous caries experience, deep cavities, and saucer-shaped preparation technique as predisposing to shorter longevity of resin-composite restorations. One brand of resin composite had a shorter survival time than the others.

The protective effect of TiF4, SnF2 and NaF against erosion-like lesions in situ.

The aim of this in situ study was to compare the protective effect of TiF4, SnF2 and NaF on the development of erosion-like lesions in human enamel. Fourteen human molars were each divided into 4 specimens, mounted on acrylic mouth appliances and worn by 7 volunteers for 9 days. In order to mimic a feasible treatment procedure for patients with voluntary or involuntary gastric reflux, the specimens were etched for 2 min twice a day (0.01 M HCl) and fluoride applications were performed every third day (2 min). The controls were treated as the other specimens except for the fluoride applications. Etch depths and surface roughness changes (Rq) were measured by white light interferometry. Compared with the control, TiF4 and SnF2 reduced the etching depth by 100% (p < 0.001) and 91% (p < 0.001), respectively, and both treatments resulted in an observable surface layer. NaF had no significant protective effect (p = 0.46). It can be concluded that although SnF2 provided significant protection for the enamel surfaces, TiF4 showed the best protection against acid attack, while NaF had no significant protective effect in this study.

The Protective Effect of TiF4, SnF2 and NaF on Erosion of Enamel by Hydrochloric Acid in vitro Measured by White Light Interferometry

The purpose of this in vitro study was to compare the protective effect of TiF4, SnF2 and NaF (all 0.5 M F) on the development of erosion-like lesions in human dental enamel. Four enamel specimens from each of 6 extracted molars were polished and embedded in epoxy resin. The enamel surfaces of 3 specimens from each tooth were treated with the different fluoride solutions for 2 min. Following fluoride treatments, the specimens were immersed in 0.01 M HCl (pH 2.0), for 2, 4 and 6 min in order to mimic a gastric reflux situation. One specimen from each tooth was used as a control and was only exposed to acid. The etching depths (in micrometres) after 6 min were: TiF4 0.8 (SD 0.8), SnF2 3.5 (SD 0.7), NaF 5.3 (SD 0.4), and 7.0 (SD 0.3) for the control specimens. Compared to the control, TiF4 protected the enamel surface from acid attack almost completely (88%), while SnF2 reduced the etch depth after 6 min by 50% and NaF by 25%.

Variations among Dentists in Radiographic Detection of Occlusal Caries

The quality of radiographic diagnosis of occlusal carries was examined with special attention to the diagnosis of lesions in dentin. Eighty-four extracted teeth, most of them with occlusal caries of different severity and some apparently sound, were radiographed. For validation purposes, the lesion depths were recorded during a drilling procedure. Ten dentists interpreted the radiographs. On average, 12% of the sound surfaces were wrongly diagnosed radiographically as having caries (false positives), 33% of the enamel lesions were identified on radiographs, and 62% of the small dentin lesions and 100% of the big dentin lesions were diagnosed radiographically (true positives). There was wide variation in the ability to identify dentin caries correctly between the observers; the sensitivity values ranged from 0.77 to 1.0 (mean 0.90) and the specificity values from 0.45 to 0.93 (mean 0.76). The dentist demonstrating the highest diagnostic quality (measured by the area beneath the receiver operating characteristics curve) had only about 9% false positives (1-specificity), while the dentist who had the lowest diagnostic quality scored caries in about 55% of the teeth in the control group. Both of them had 96% true positives. The tendency to make false-positive registrations in the dentin adjacent to enamel seems to be a major problem in radiographic diagnosis of occlusal caries. The radiograph has significant value in the diagnosis of occlusal dentin caries, but the great variations between observers indicate the need for training and calibration.

Reliability of Two Clinical Scoring Systems for Dental Erosive Wear

The aim of the study was to evaluate and compare two dental erosive wear scoring systems, the Visual Erosion Dental Examination (VEDE) and Basic Erosive Wear Examination (BEWE). Seventy-four tooth surfaces (photographs) and 562 surfaces (in participants) were scored by 5 (photographs) or 3 (in participants) clinicians using both scoring systems. The surfaces in the photographs were scored twice. The level of agreement was measured by weighted kappa (ĸw). Inter- and intraexaminer agreement showed small variations between the examiners for both systems when scoring the photographs. Slightly higher mean ĸw values were found for VEDE (ĸw = 0.77) compared with BEWE (ĸw = 0.69). When scoring the surfaces in the clinical examination the mean ĸw values for the two systems were equal (ĸw = 0.73). Interexaminer agreement using VEDE was calculated to see how differentiation between enamel and dentine lesions influenced the variability. The highest agreement was found for score 0 (sound, 86%) and score 3 (exposure of dentine, 67%), while the smallest agreement was shown for score 1 (initial loss of enamel, 30%) and score 2 (pronounced loss of enamel, 57%). The reliability of the two scoring systems proved acceptable for scoring the severity of dental erosive wear and for recording such lesions in prevalence studies. The greatest difficulties were found when scoring enamel lesions, especially initial lesions, while good agreement was observed when examining sound surfaces (score 0) and dentine lesions (score 3).

Highly Acid SnF2 and TiF4 Solutions

In a previous in vitro study, a considerable fluoride uptake was found in scaled root surfaces following treatment with a TiF4 solution (1.1 M F, pH 1.0). In spite of the

Caries assessment and restorative treatment thresholds reported by Swedish dentists.

The aim was to study any variability in approximal and occlusal caries diagnoses and restorative treatment decisions among Swedish dentists. The material consisted of a pre-coded questionnaire sent to a random sample of 923 dentists with 4 items concerning approximal and occlusal caries diagnosis and restorative treatment decisions. Responses were received from 651 (70.5%) dentists. In an adolescent with low caries activity and good oral hygiene, more than 90% of the dentists stated that they would not automatically restore a primary approximal caries lesion if its radiographic appearance did not show obvious progression in the outer 1/3 to 1/2 of the dentin. Moreover, 67% of the dentists would only consider immediate restorative treatment of an occlusal surface if obvious cavitation and/or radiographic signs of dentin caries could be observed. When diagnosing questionable occlusal caries, the dentists largely relied on the radiographic appearance. Concerning both approximal and occlusal caries, the threshold for restorative treatment differed between the metropolitan regions in Sweden, and younger more often than older dentists would postpone restorative treatment of approximal caries until the lesion had reached a relatively advanced stage of progression. The responses also showed that dentists in private practice would restore approximal caries at an earlier stage of progression than the dentists in the Public Dental Health Service.

The erosion-inhibiting effect of TiF4, SnF2, and NaF solutions on pellicle-covered enamel in vitro

Objective. The aim of this study was to compare the protective effect of TiF4, SnF2, and NaF treatment on the development of erosion-like lesions in pellicle-covered human enamel. Material and Methods. Twelve human molars were each divided into 5 specimens, 4 of which were immersed in saliva for 2 h. Three pellicle-covered specimens from each tooth were treated with a TiF4, SnF2, or NaF solution (all 0.5 M F) for 2 min. Control specimens, one with and one without pellicle, were included. Immersion in acid (0.01 M HCl) was carried out stepwise (2+2+2+2 min). The etching depths (in µm) were measured using white light interferometry. Results. Compared with the control with pellicle, TiF4 reduced enamel loss by 100% after 2 min and by 24% after 8 min of acid exposure. The corresponding values for SnF2 were 45% and 14%. NaF provided no significant protection of the surface. The pellicle-covered specimens showed reduced lesion depths after 6 and 8 min compared to the controls without pellicle. Conclusions. TiF4 gave the best protection against acid attack. SnF2 provided significant protection only after 2 min of acid exposure, while NaF had no significant protective effect.

Changes in the Treatment Concept for Approximal Caries from 1983 to 2009 in Norway

The aim was to measure variations in threshold for operative treatment of approximal caries in permanent teeth and the use of restorative materials, compared with results from studies conducted in Norway in 1983 and 1995. In 2009, a precoded questionnaire was sent electronically to 3,654 dentists with E-mail addresses in the member register of the Norwegian Dental Association. The questions were related to caries, treatment strategies and choice of dental materials. Replies were obtained from 61% of the dentists after two reminders. Restorative treatment of approximal lesions confined to enamel, based on radiographic appearance, was proposed by 7% of the dentists, compared with 66% in 1983 and 18% in 1995. Younger dentists, significantly more often than older, would defer operative treatment of approximal lesions until the lesion was visible in dentine. While tunnel preparation most often was the preparation of choice in 1995 (47%), saucer-shaped preparation was most favoured in 2009 (69%). Tunnel preparation was only preferred by 4% of the dentists. Resin composite was the restorative material preferred by 95%, compared with 16% in 1995. The corresponding values for conventional glass ionomer cement (GIC) were 1 versus 22%, for resin-modified GIC 1 versus 7%, and for a combination of GIC and resin composite 2 versus 22%. Compomer was preferred by 1% of the respondents. The authors conclude that treatment concepts for approximal caries have changed considerably during the last 26 years. In 2009, only 7% of dentists reported that they would treat approximal caries operatively before the lesion reached dentine.

An in vitro study on the effect of TiF(4) treatment against erosion by hydrochloric acid on pellicle-covered enamel.

The aim of this in vitro study was to examine the effect of fluoride treatment on pellicle-covered enamel exposed to an acidic challenge simulating gastric reflux. Sixteen bovine and 16 human teeth were sectioned into four pieces, divided into four groups: (1) control, (2) 2-hour pellicle, (3) TiF4, and (4) 2-hour pellicle + TiF4, and subsequently subjected to 3 ml 0.01 M HCl stepwise for 4 + 4 + 4 min. The acid was analysed for calcium by atomic absorption spectroscopy. TiF4 reduced Ca release from enamel by 76, 57 and 56% following the 4 + 4 + 4-min acid exposures, respectively, in bovine and 44, 54 and 54% in human enamel. These results suggest that treatment of enamel with a TiF4 solution, with or without pellicle removal, may provide protection for the enamel against acid attack.